Individuals afflicted with diabetes mellitus experience varying degrees of malfunctioning of the body cells which produce insulin. Insulin is necessary for proper metabolism of glucose in the blood.
The historical treatment of a diabetic condition was to give periodic injections of insulin and to attempt to control the diet so that the injected insulin could handle the carbohydrate intake. This was somewhat unsatisfactory since the insulin injections were not generally timed to concide with carbohydrate intake. Situations were thus created wherein the amount of insulin present was either in excess of or less than that required to handle the specific blood glucose level at any given time. Such a situation is especially severe when the diabetic is under stressed conditions, such as surgery or childbirth for example.
Various systems and apparatus have been proposed to analyze the blood concentration and to infuse insulin or glucose based upon such analysis to better control the blood glucose to within desired ranges. A significant advance in the art is described in Diabetes, Vol. 23, No. 5, pp. 389 -404 (1974). Apparatus is described having a computer which operated an infusion pump to infuse insulin or glucose based upon analytical blood glucose values. The computer derives the output signals for pump operation from algorithms based upon hyperbolic tangentail functions. While this prior art computer control had many advantages, it had the distinct disadvantage that the responses did not always satisfactory provide adequate control. Also, the apparatus provided only limited flexibility in the selection of specific operating conditions for particular individuals whose blood glucose concentrations were being controlled by the apparatus.
There is thus a need for apparatus for improved control of blood glucose concentration and which also enables a higher degree of flexibility in selecting specific operating conditions.